1. Field of the Invention
This invention relates to a composition of fluoroborate complex and sulfuric acid containing wetting agents for cleaning containers comprised of aluminum and alloys thereof.
2. Description of the Prior Art
Containers comprised of aluminum and alloys thereof are produced in a drawing and forming operation, referred to as drawing and ironing, which results in the deposition of lubricants and forming oils on the surface. In addition, residual aluminum fines, i.e., small particles of aluminum, are deposited on the interior and exterior surfaces of the container during the forming operation. Prior to any processing steps, such as conversion coating and sanitary lacquer deposition, the surfaces of the aluminum containers must be cleaned and water-break-free so that there are no contaminants which prevent further processing and which render the containers unacceptable for use.
Acid cleaners including hydrofluoric acid and boric acid have been employed to clean aluminum surfaces and to remove aluminum fines deposited thereon. U.S. Pat. No. 4,009,115 employs sulfuric acid and hydrofluoric acid to clean aluminum surfaces at temperatures of 90.degree. to 135.degree. F. and a pH less than 2. No where in the reference does the combination include a boric acid component or a fluoroborate component such as taught in the instant invention. U.S. Pat. Nos. 3,228,816, 3,106,499, and 2,682,502 teach the cleaning of aluminum surfaces employing nitric acid cleaners combined with hydrofluoric acid and boric acid. These references, nevertheless, use high temperatures in the range of 160.degree. to 212.degree. F. in order to remove dissolved aluminum fines and to remove the lubricant forming oils so that the surface is rendered water-break-free. Because of the high temperatures at which cleaning is accomplished, the processing equipment employed to heat the cleaning compositions, particularly the fire tubes of gas fired heat exchangers, are susceptible to corrosion. Furthermore, the high temperatures increase operating costs and fuel consumption. The fluoride when present in high concentrations can attack the metal surfaces and etch the surface which is undesirable, especially when cleaning of containers is to be effective. Moreover, none of these references teach the use of sulfuric acid in their cleaning solutions. The present invention overcomes all of the above mentioned disadvantages.